1. Field of the Invention:
The present invention relates to cryostats. In particular, the present invention is a cryostat for cooling the central processor of a computer system.
2. Description of the Prior Art:
The performance of certain electrical or electronic devices can be altered, and in fact enhanced, by operation at cryogenic temperature. Cryostats have been developed to permit operation of such devices at the extremely low temperature which is required. Examples of prior art of cryostats are illustrated in U.S. Pat. No. 3,122,004 by Aberle et al, U.S. Pat. No. 3,133,144 by Cottingham et al, and U.S. Pat. No. 4,502,296 by Ogata et al. In general, these devices use a Dewar type construction, with an inner and an outer vessel which are connected together to define a vacuum chamber. The inner vessel contains the cryogenic coolant (for example, liquid nitrogen or liquid helium) used to cool the particular electrical or electronic device. The vacuum maintained between the inner and outer vessels provides thermal insulation between the cryogenic coolant within the inner chamber and the ambient room temperature outside of the outer chamber.
As the computing power of computers has been increased, the demand for increasingly higher operating speeds of the integrated circuits of the computer's central processor has presented a significant technical challenge. One approach for achieving higher speeds is to use a semiconductor material (such as gallium arsenide) which is capable of yielding higher operating speed devices than is silicon. The disadvantage of this approach, however, is that the material growth and integrated circuit fabrication techniques are far more advanced in silicon than in any other semiconductor material.